


The Souls (Undertale AU)

by TheTeamJBJBLABMB



Category: Sanders Sides (Web Series), Undertale (Video Game)
Genre: Other
Language: English
Status: In-Progress
Published: 2020-11-08
Updated: 2020-11-20
Packaged: 2021-03-08 22:53:51
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, Major Character Death
Chapters: 3
Words: 2,676
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27444439
Author URL: https://archiveofourown.org/users/TheTeamJBJBLABMB/pseuds/TheTeamJBJBLABMB
Summary: Based a Little Bit on 'The Thought' comic (the souls' communication and such)Seven Human Souls...and then anyone can become a god. Well, the Humans intend to beat the monsters to it. Thomas Sanders is the child chosen for the role, the one to absorb the souls that have been collected for the experiment. Absorbing the souls, Thomas is sent to the underground to eradicate all monsters there.The results are...not so destructive.
Relationships: Couldn't really think of a relationship
Comments: 6
Kudos: 13





	1. Once Upon a Time

Dr. Whitman was of the belief that if something was done for the greater good, it could never be wrong. This belief, of course, was up to interpretation, as beliefs often were, but a general portion of the population would likely disagree with this assumption, since the greater good for an individual is not the greater good of everyone. For example, the greater good for all of the Humans who agreed that Monsters must be eradicated directly conflicted with those who believed they should be left alone, and, of course, the souls sacrificed for their goal.   
The souls were taken from children in the local orphanage, children that were considered worthy of sacrifice, though nobody was quite sure what constituted a worthy Human. The pickings of the souls didn’t help much, since many of the children picked were ‘fit additions to society’  
The researchers and scientists had not cared.   
Funny how the human race is so ready to sacrifice anything it has to in order to get a ‘happy ending’, even if it means ending lives. It had occurred so much in the past that any history class in any school was agonizingly boring, a continuous train of wars, battles, small innovations, and then more conflict. Like now; the war between monsters and humans, the battle to force them underground, the discovery of the monster’s legends, the barrier, and the souls needed to break said barrier, and now, the end of the underground…  
Yes, it was repeating all over again.   
Thomas Sanders was the child picked for the experiment, an ordinary child from an ordinary family, from an ordinary background; another question of what exactly made one ‘worthy’ erupted after this choice. Sanders was just another kid, his mind so focused on hopes and dreams that he didn’t quite understand what the adults were trying to get him to do. Why did he need to fight these monsters? Why did he need to hurt people who had never hurt him?  
And why did he need to absorb these heart thingies?  
Why did they call them...souls?  
After the absorption of the souls, Thomas Sanders promptly blacked out, and when he awoke, he was no longer alone. Within his mind, he could hear voices, inputs from six different places, six different tones, all of them asking, begging, yelling. “Wake up!”   
So, Thomas did.  
When he awoke, it was like the voices had never been added, like none of the events of the previous day had ever happened. Thomas was still expected to fight, though now he had to encourage the souls to fight, their attacks so bizarre that the scientist’s mouths gaped as they watched them. Thomas was still expected to learn anything and everything about Monsters, but now there were questions directed at him that were answered by the voices inside his head instead. And finally, Thomas was still expected to answer the interviewer’s questions about how he was doing, though now the interviewer (or therapist, he supposed) was a lot more focused on his mental health. Did he feel stable? Did he feel crazy? Was he going insane, or was he feeling normal as ever?  
Thomas was so confused.  
Besides giving him a little more care and attention and giving him weird scenarios and such, the scientists never mentioned the voices, or even what he had absorbed. He knew the voices must come from the little heart-shaped thingies, but he still didn’t know what they were.   
Thomas was so confused.  
\----  
It didn’t take a genius to tell the story of Mt. Ebott.   
It was a place that nobody went to, a mountain on the farthest side of Ebott village, up vast hills and peaks. There was said to be a hole into the mountain, and falling down that hole would be the last anyone ever saw of you, according to legend. Those who fell never returned.   
Thomas Sanders didn’t exactly fall.  
It was more accurate to say he was dropped.   
He landed limply in the ruins, the resulting thump loud and coupled with a cry of pain. He checked to make sure he hadn’t broken anything like he’d seen other kids do when they fell down on the playground, but there wasn’t anything wrong. No, the only thing wrong was that nobody was coming back for him, even though this was an obvious ‘man overboard’ situation.   
He waited, and waited, and waited…  
But nobody came.


	2. Your Best Friend/Fallen Down/

**Summary for the Chapter:**

> Seven Human Souls...and then anyone can become a god. Flowey has to question how the Humans came to the conclusion that a child was the best person to send. Toriel can't wrap her mind around this concept either, nor can she understand the 'episodes' this particular child has.

Flowey the flower was...confusing.  
He had popped up in a patch of grass in the middle of an otherwise dark room, and when he had, it’d been from nowhere. He had introduced himself in an excited, bubbly manner, and he’d talked about love and such, but even Patton- the cyan soul who showed everyone untamed amounts of affection- was put on edge by its fake smile and its little speech. “Friendliness Pellets?” Patton asked, though he knew Flowey couldn’t hear him. “Why not just give us a hug or something?”  
And then, when the friendliness pellets had come out, Virgil, in a panic, had activated his powers, and the words ‘Stockholm Syndrome’ and ‘Mer-Lawyer’ popped up, blocking the pellets from hitting Thomas’ exposed soul. Flowey’s eyes widened, and his stem leaned back a little, petals bending in question. “What...what was that?” the flower asked, but Thomas was paying more attention to Virgil, who was reporting back that the ‘friendliness pellets’ had been a magical attack, one that was meant to hurt Thomas.   
Thomas blinked himself back into focus, just in time to see the ring of ‘friendliness pellets’ around his heart before Flowey was blasted away by a ball of fire, and another monster intervened, her voice soft.   
“What a terrible creature,” she whispered, her voice filled with hatred. “Torturing such a poor, innocent youth.”  
The monster introduced herself as Toriel, and as she explained exactly what the ruins were, and what she was there for, Thomas found himself trusting her more and more. The souls found themselves struggling with the same thing.   
“Should we trust her?” Janus asked, his eyes drifting towards Virgil. Virgil shrugged, shrinking under their expectant looks.   
“She hasn’t given any indication of attacking us,” Logan pointed out, and Virgil sighed in relief as the attention was turned from him. “In fact, she’s been leading us through these puzzles without any deceitful intentions so far, and she’s even guided us across an entire path of spikes, spikes that surely would have hurt us had she not led us through them.”  
“She’s trustworthy, Thomas! She’s like a mom!” Patton giggled.   
“-Man? Human!”  
Thomas jolted out of his thoughts, out of the white void that the souls spent their time in, and back into reality. He blinked, looking up at Toriel, whose expression expressed concern. “Are you alright, my child? You’ve been zoned out for quite a while now…”   
“I’m ok,” Thomas replied, giving her an easy smile. “What’s next?”  
\----  
Toriel was unsure how to react to this child.   
Thomas’ eyes were filled with an uncanny amount of knowledge, as if he knew more than he was letting on. He hadn't panicked at all when he’d come out of the encounter with that terrible monster, and he’d been comfortable with her, something she had been hoping for, but hadn’t expected. Not only that, but he had zoned out for a short time, unresponsive to Toriel’s voice.  
And now, here they were, standing in front of a dummy, Thomas’ face a mask of confusion. Toriel stifled a laugh. “This is a dummy. You’ll be practicing talking to it, Thomas,” she explained, and Thomas blinked, even more bewildered.   
“You’ll be pushed into interactions like this. Talking and sparing are the best decisions,” Toriel elaborated. Thomas winched, holding his head, and Toriel began to panic.   
“Child? Are you-oh.”   
Thomas was smiling and laughing, and under his breath, shaking his head with something Toriel could only describe as fondness. He stepped forward, and said hello to the dummy, engaging it in a one-way conversation, pausing every so often to ‘hear it speak’. Finally, he waved goodbye and returned to Toriel’s side, a grin still on his face.   
“Okay, I talked to them! Now what?”   
Toriel smiled.

**Notes for the Chapter:**

> I hope you enjoy this chapter. Time to incorporate the Sides into Thomas' shenanigans.   
> I wonder if you can figure these things out:  
> What are the attacks based on? (This might become more obvious later on)  
> What is the importance of the words in Virgil's defensive magic?  
> What are the titles of each chapter referencing? (will also become more obvious later on)


	3. Heartache/sans/Nyeh Heh Heh!

**Summary for the Chapter:**

> Thomas and co. finally find a way to leave Toriel's home and the Ruins, and emerge into Snowdin. Patton finds a kindred spirit.

Thomas’ encounters so far had been amazing!  
He’d met a Froggit, who’d blushed as Thomas complimented him, a Whimsun who had been afraid of him even when Thomas attempted to console him, and other monsters like the Vegetoids who wanted to feed him, the Migosps who enjoyed being alone, the Modsmals who loved laying down with him or wiggling with him, and he’d even met a ghost named Napstablook, who reminded them somewhat of Virgil, what with their nervous demeanor and eager-to-please attitude. Thomas felt a lot more positive after cheering for ‘dapper blook’, and when he’d arrived at Toriel’s, it had been with a satisfied air.   
Now, though, sitting on the edge of a twin-sized bed and staring at a slice of Butterscotch-Cinnamon pie that had been left on the floor, he wondered where he would go from here. Thanks to Logan, they knew that the stairs in the entranceway of Home were likely the way he’d need to go to reach the exit of the ruins, but the question was...how?  
“We’ve tried asking her,” Roman whined. “She just rebuffed us with a snail fact”  
“It was a good snail fact!” Remus interjected, and Roman threw him a half-hearted glare.   
“Yeah. Sure.”   
“And we’ve already tried leaving through the stairs, as well,” Janus added, rubbing the bridge of his nose as if fighting a headache. “She found us before we could reach the door, and then brought us back. I don’t think we can easily go that way.”   
“We could try asking her about the exit?” Patton contributed meekly.  
“Not likely. She’d probably just distract us again. No, it seems as if a use of our powers is in order. We’ll keep her back from the door long enough for us to exit the ruins.”   
Thomas thought that seemed kind of cold, but what other choice did they have? They had to move on, and if this was the way to do it, then so be it. They geared up Logan’s notebooks and Remus’ hands to act as a shield and block the staircase, and then Thomas was off, making his way down the purple halls towards a towering door at the end. “That must be it,” Patton deduced, voice filled with trepidation.  
Thomas pushed the door open, looking out into the hall ahead, another door placed at the end. He started forward.   
“Child! Wait!”   
Thomas turned around, his mind filled with the shocked exclamations of the other souls. Toriel was standing in the exit, her face filled with sadness, a large cut stretching across her arm. Patton began panicking immediately. “She got hurt by the shields! Thomas, please let me-!”  
“Go ahead,” Thomas said out loud, and a moment later, Patton’s cookie ‘attack’ launched, and tons of spinning cookies were absorbed into Toriel’s body, the cut stitching itself back together, healing over.   
Toriel looked down at the healing cut, and then at Thomas, who was still standing in the middle of the hall with a smile on his face. “Don’t worry about me, Toriel. I’ll be ok...I have guardians protecting me!” For that is what the souls seemed to be; Guardians to keep him safe and help him get through the Underground.   
Toriel still seemed reluctant to let him go, but something in his eyes must have convinced her, because she simply approached to give him one last hug, squeezing him tightly before leaving, only stopping once to look back.   
And Thomas left.  
\----  
The pathway in front of Thomas was unnerving. Closely grouped trees surrounding the path in a straight line like uniform soldiers, the path tapering off into a wooden bridge with bars stretching across it. One lone branch laid across the path, and when Thomas approached it, he knew it wouldn’t be able to be picked up, so any hope of moving that out of the way of any clumsy person coming by left his mind.   
And then, as he passed by, the loud crack of the stick breaking served to warn Thomas that whatever presence was nearby wasn’t any low-level monster. The power level that must have taken showed that of an admirable foe. Not that Thomas wanted one of those. He wondered if a monster that powerful would enjoy being friends with him. He hoped so.   
He walked a little further, preparing to slip through the wooden bars of the bridge, but something within him froze, and suddenly, he couldn’t move. “Thomas, are you alright!?” Patton cried, at the same time that Virgil warned them that someone was coming.   
“Human.”  
The mindscape shuddered, Thomas’ nerves raining supreme.  
“Don’t you know how to greet a new pal? Turn around and shake my hand.”  
Thomas felt compelled to move, and without his permission, his body pivoted on his heel and faced the being. For some reason, his sight was fading in and out. He was so nervous. Who was this person? How did they have so much control over Thomas’ body?  
His hand reached out despite his attempts to stop it, and the other’s hand locked onto his, shaking it. The resulting noise was indescribable. Somewhere between a fart and a raspberry one might blow to tease someone.  
The mysterious stranger laughed.  
“The whoopie cushion in the hand trick!” the skeleton exclaimed, his voice lighter and friendlier. “It’s always funny!”   
Thomas snorted, an exhale of relieved air, and then began laughing at the ridiculousness of it all. He’d been so worried that this skeleton was going to hurt him, or worse, and in the end, he’d had no reason to be afraid.  
“Anyway, I’m Sans. Sans the Skeleton. I’m supposed to be on the lookout for humans right now, but...I don’t really want to capture anybody,” the skeleton’s smile was fixed, but Thomas could still tell that he was smiling.   
“Well, we have a funny man,” Janus whispered.   
As Sans spoke about his brother, and pointed out a figure approaching them in the distance, Thomas wondered if he was hallucinating or not. Had this been what the scientists had warned him about? Dangerous monsters, they had said, but he hadn’t experienced anything very...dangerous. Flowey didn’t really count.   
Even though Sans had talked about Papyrus being a human hunter, from Thomas’ position behind ‘that conveniently shaped lamp’, Papyrus appeared to be more of a bubbly clutz, eager to please in an effort to ‘join the royal guard’  
As Sans made pun after pun, and Papyrus got more and more frustrated, Thomas could practically feel the vibrations caused by Patton’s laughter. The boy was rolling around the mindscape, giggling breathlessly, and the other sides’ reactions varied from indifferent to joining Patton on the floor. Thomas could barely hold back the laughter he wanted to let out, and as Papyrus left the scene, and Sans called him out, Thomas burst into loud guffaws, finally able to join Patton in rolling around on the ground.   
Patton’s mouth was spouting so many skeleton-related puns, and while he wasn’t aware of it, so was Thomas’. “I guess your brother doesn’t have the stomach for your puns! He looked like he had a BONE to pick with you!” he kicked out as his laughter got louder, and felt a spark of joy when Sans’ surprised expression turned to one of genuine happiness. “Oh, don’t worry, I’ve got an EYE out for more of those! I find them very HUMERUS,” Sans retorted, and Patton’s laughter- and by extension, Thomas’- turned silent as he writhed on the ground  
When Thomas had finally gathered himself a bit more, he turned back to Sans with a smile. “Thanks. I needed that! I felt that in my BONES.”   
With leftover giggles and real smiles filled with joy, Sans asked him to indulge Papyrus’ need to meet a human, and Thomas couldn’t help but agree. Even as Sans left, his smile didn’t fade.   
If anything, it just grew wider.

**Notes for the Chapter:**

> Sorry this took a while; everything has been crashing down, but my promise that I wouldn't leave work on a hiatus if I didn't absolutely have to stood strong, and I finally got the motivation to get this done. I hope you enjoy it, and thank you for reading this!

**Author's Note:**

> This is such an interesting AU, and I really wanted to explore it, but wasn't sure how I could incorporate the sides. This is what I decided on, and I hope you enjoyed!


End file.
